http://xmlgraphics.apache.org/fop/: Apache FOP (Formatting Objects Processor) is the world's first print formatter driven by XSL formatting objects (XSL-FO) and the world's first output independent formatter. It is a Java application that reads a formatting object (FO) tree and renders the resulting pages to a specified output. Output formats currently supported include PDF, PCL, PS, AFP, TIFF, PNG, SVG, XML (area tree representation), Print, AWT and TXT. The primary output target is PDF. (Apache Software Foundation) 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id: PDFFilter.java 1610839 2014-07-15 20:25:58Z vhennebert $ */

package org.apache.fop.pdf;

import java.io.IOException;
import java.io.OutputStream;


PDF Filter class.
This class represents a PDF filter object.
Filter implementations should extend this class.


This work was authored by Eric Schaeffer and Kelly A. Campbell.


/**
 * <p>PDF Filter class.
 * This class represents a PDF filter object.
 * Filter implementations should extend this class.</p>
 *
 * <p>This work was authored by Eric Schaeffer and Kelly A. Campbell.</p>
 */
public abstract class PDFFilter {
    /*
     * These are no longer needed, but are here as a reminder about what
     * filters pdf supports.
     * public static final int ASCII_HEX_DECODE = 1;
     * public static final int ASCII_85_DECODE = 2;
     * public static final int LZW_DECODE = 3;
     * public static final int RUN_LENGTH_DECODE = 4;
     * public static final int CCITT_FAX_DECODE = 5;
     * public static final int DCT_DECODE = 6;
     * public static final int FLATE_DECODE = 7;
     */

    
Marker to know if this filter has already been applied to the data

/**
     * Marker to know if this filter has already been applied to the data
     */
    private boolean applied;

    
Check if this filter has been applied.

Returns:true if this filter has been applied
/**
     * Check if this filter has been applied.
     *
     * @return true if this filter has been applied
     */
    public boolean isApplied() {
        return applied;
    }

    
Set the applied attribute to the given value. This attribute is
used to determine if this filter is just a placeholder for the
decodeparms and dictionary entries, or if the filter needs to
actually encode the data. For example if the raw data is copied
out of an image file in it's compressed format, then this
should be set to true and the filter options should be set to
those which the raw data was encoded with.

Params:
  • b – set the applied value to this
/**
     * Set the applied attribute to the given value. This attribute is
     * used to determine if this filter is just a placeholder for the
     * decodeparms and dictionary entries, or if the filter needs to
     * actually encode the data. For example if the raw data is copied
     * out of an image file in it's compressed format, then this
     * should be set to true and the filter options should be set to
     * those which the raw data was encoded with.
     *
     * @param b set the applied value to this
     */
    public void setApplied(boolean b) {
        applied = b;
    }

    
return a PDF string representation of the filter, e.g. /FlateDecode

Returns:the filter PDF name
/**
     * return a PDF string representation of the filter, e.g. /FlateDecode
     *
     * @return the filter PDF name
     */
    public abstract String getName();

    
Returns true if the filter is an ASCII filter that isn't necessary
when encryption is active.

Returns:boolean True if this filter is an ASCII filter
/**
     * Returns true if the filter is an ASCII filter that isn't necessary
     * when encryption is active.
     * @return boolean True if this filter is an ASCII filter
     */
    public boolean isASCIIFilter() {
        return false;
    }

    
return a parameter dictionary for this filter, or null

Returns:the decode params for the filter
/**
     * return a parameter dictionary for this filter, or null
     *
     * @return the decode params for the filter
     */
    public abstract PDFObject getDecodeParms();

    
Applies a filter to an OutputStream.

Params:
  • out – contents to be filtered
Throws:
Returns:OutputStream filtered contents
/**
     * Applies a filter to an OutputStream.
     * @param out contents to be filtered
     * @return OutputStream filtered contents
     * @throws IOException In case of an I/O problem
     */
    public abstract OutputStream applyFilter(OutputStream out) throws IOException;

}